Benjamin Brink/The OregonianJennifer Blair (right) manager of Walgreens at 1620 NE Grand Ave. in Portland, said the store is prepared for the switch to paper bags. Mayor Sam Adams will visit the store at 12:30 pm Saturday to mark the change -- and help hand out free reusable bags.

"Bring your BAG, bring your BAG, bring your BAG, BAG, BAG," he sings in a radio ad set to the tune of the "William Tell Overture."

In another, the sound of a tattoo gun buzzes as the mayor yelps: "Sure you can tie a string around your finger, but why not do what I'm doing and get a reminder tattoo?"

The city's ban on plastic checkout bags starts Saturday, and the mayor wants to remind shoppers to bring reusable bags so stores don't have to dole out paper ones. The ban -- the first in Oregon -- affects major grocers and large retailers with pharmacies, though paper bags are already the norm at Fred Meyer's 10 Portland locations, New Seasons Market stores and Whole Foods.

The city is spending about $10,000 on the radio ads and bus ads. Portland is also giving away 10,000 reusable bags through social-service agencies such as Elders in Action and the Oregon Food Bank. Target, Walgreens and Walmart also will offer free reusable bags at Portland stores while supplies last.

What stores are affected?Supermarkets with $2 million or more in gross annual sales such as Safeway, Albertsons and QFC, plus retailers of at least 10,000 square feet that have pharmacies, such as Target, Walmart, Walgreens and Rite Aid.

What's next? Portland's experience over the next 60 to 90 days will shape whether other cities -- or the state -- adopt bans, said Joe Gilliam, president of the Northwest Grocery Association. The association favors a statewide approach, Gilliam said, arguing that a patchwork of local ordinances would confuse retailers and consumers.

Legislators have no plans to take up the issue in the February 2012 session, said Sen. Mark Hass, D-Beaverton. But it could return at a later session, Hass said.

What about elsewhere? Portland joins cities such as Bellingham, Wash., and San Francisco. In Oregon, Newport has a hearing on the topic set for Oct. 17. Some Corvallis residents are pushing a ban, too.

That worries Oregon grocers, who could face different rules -- such as mandatory customer fees on paper bags -- in different jurisdictions, Gilliam said.

In Portland, retailers will cover the extra cost of giving customers paper instead of plastic -- estimated at $12 million a year, according to the grocery association. "It's not a bad alternative, it's just an expensive alternative," Gilliam said.

Backers, however, cite the environmental cost of plastic bags, which are blamed for hurting wildlife and clogging landfills.

Will Portland broaden its ban? Lisa Libby, Adams' planning and sustainability director, said officials have no plans to include other businesses such as convenience stores, farmers markets or restaurants.

What are consumers saying?Some consumers like plastic bags because they reuse them to pick up dog waste and for other tasks. At the Safeway near Portland State University on Friday, Cindy Reinert said she has long used them to carry her lunch.

But Elaine Cohen, another shopper, was already toting four reusable bags, a habit she developed in recent years. "I don't have a problem with it," Cohen said. "I did run into someone yesterday who was really grumpy about the change."